The rising prevalence of obesity in the U.S. over the past several decades and the accompanying spread of adverse long-ranging health effects pose serious public health and economic consequences. At least half of women of reproductive age now enter pregnancy at a high body mass index (BMI, kg/m2), and the majority experience pregnancy-associated weight gains in excess of Institute of Medicine (IOM) guidelines, leading to increased perinatal and chronic health risks for both mother and child. Limited intervention research has indicated moderate improvement in short-term maternal diet and gestational weight gain, with little evidence of long-term adherence. The well-documented inadequacies of these and traditional weight-loss interventions relying on existing paradigms suggest the need for innovations that allow for a shift in the theoretical framework underlying the determinants of eating behavior. Recent findings from basic research in neuroscience suggest that the brain reward response to food is a critical element that is currently absent in this theoretical framework. However, this quickly-expanding body of work has not been incorporated into population-based research to date. This observational study will address this knowledge gap by examining the implications of findings on the importance of the food reward response for understanding and influencing maternal diet and weight change. The overarching goal of this research is to advance understanding of the determinants of eating behavior in order to inform future development and testing of novel interventions for improving maternal diet and weight change, leading to improved maternal and child health trajectories. The primary purpose of this observational cohort study is to examine the role of food reward in maternal diet and weight change during pregnancy and postpartum. The study will further examine the importance of food reward in the context of behavioral control and other related aspects of eating behavior, as well as weight-related biomedical, psychosocial and behavioral factors including genetics, physical activity, stress, sleep and depression. Four hundred and fifty women of varying baseline weight status will be enrolled early in pregnancy (before 12 weeks postpartum) and followed until 1 year postpartum. Assessments will occur at baseline (<12 weeks postpartum), during pregnancy at 13-18 weeks gestation, 16-22 weeks, and 28-32 weeks, and postpartum at 4-6 weeks, 6 months, 9 months and 12 months. Measures will include assessments of food reward and related constructs, dietary intake, other health behaviors, and anthropometrics. Clinical data and biological specimens will be obtained. Infant anthropometrics and feeding practices will also be assessed. Primary exposures include aspects of food reward and behavioral control, which will be assessed in multiple ways to maximize information and utility. Primary outcomes include gestational weight gain, postpartum weight retention and dietary quality.